1. Field of Invention
The present invention is directed to a display drive device for driving an electro-optical device, for example, a liquid crystal display device, an electrophoresis device such as an electronic paper, an EL (Electro-Luminescence) display device, a field emission device (surface-conduction electron-emitter display), and the like. Further, the present invention is directed to an electronic apparatus comprising the above electro-optical devices.
2. Description of Related Art
Conventionally, setup information to change and set a drive voltage, such as an electronic volume value that is information for setting contrast, is transmitted from an external system comprising a microcomputer and the like in an LCD (Liquid Crystal Display) driver.
In this regard, in order to reduce a cumbersome setup of the setup information in assembling a display device comprising an LCD driver, an LCD driver has been proposed where the setup information is pre-stored in a nonvolatile storage unit and, based on the stored setup information, an electronic volume value is automatically set when the power is turned on.
Meanwhile, for example, a buyer who has obtained an LCD driver from a supplier sometimes takes notice that only a partial display region of a display unit is employed in a display drive. Hence, in assembling a display device using an LCD driver, the screen information, such as the resolution of a display unit, pixels to be driven, or an arrangement of sub-pixels (dots) constituting pixels, should be additionally set. This setup has conventionally been performed by reading a variety of commands from the conventional external system into an LCD driver.
Further, after setting an electronic volume value in that way, a register in which the information has been set may be suddenly cleared due to an external factor, such as an electrostatic discharge (ESD). Due to such a situation, an LCD driver cannot normally perform its display unless the electronic volume value is reset in the cleared register. The phenomenon where a setup is cleared by the above external factor similarly occurs due to a display grayscale characteristic value that adjusts an applied effective voltage for grayscale representation by pulse width modulation (PWM), a temperature compensation value that adjusts a change in a supply voltage accompanied with a change in environmental temperature, or a voltage generating circuit for transformation and supply of a power voltage, in addition to the setup information of the electronic volume value, in view of the fact that a register itself is suddenly cleared due to ESD and the like.
The present invention has been made in view of the above circumstances. Accordingly, an object of the present invention is to provide a display drive device, an electro-optical device, an electronic apparatus, and a drive setup method of the display drive device so as to automatically set screen information in a display unit. Further, it is another object of the present invention to provide a display drive device, an electro-optical device, an electronic apparatus, and a drive setup method of the display drive device so as to suppress abnormal display caused by clearing of the setup information.